The present invention relates to a metal gasket with a continuous bead interposed between a cylinder head and cylinder block of an internal combustion engine.
Conventionally, in a cylinder head gasket interposed between a cylinder head and a cylinder block of an internal combustion engine, especially in case the gasket seals a water hole located close to an area between two combustion holes of the engine where an interval between the combustion holes is narrow, there is a difficulty in sealing the water hole.
Also, in recent years, in order to secure a durability of the gasket itself, a metal gasket has been used widely. In the metal gasket, in case an interval or intermediate area between the combustion chamber holes adjacent to each other is narrow, beads around these combustion chamber holes are connected to each other to form a common portion in the intermediate area between the combustion chamber holes. In this case, curved portions surrounding the combustion chamber holes diverge at an intersecting portion from the common portion. However, if it is tried to form a water hole outside the intersecting portion close to the center of the intermediate area between the combustion chamber holes, it is difficult to surround a periphery of the water hole by the curved portions of the bead.
Accordingly, an object of the invention is to provide a metal laminate gasket with a continuous bead, in which a water hole can be formed outside the bead intersecting portion and close to a center of the intermediate portion between the combustion chamber holes.
Another object of the invention is to provide a metal laminate gasket as stated above, in which intermediate portion between the adjacent combustion chamber holes and the water hole can be effectively sealed by bead portions.
Further objects and advantages of the invention will be apparent from the following description of the invention.
A metal laminate gasket of the invention is used for an internal combustion engine having a plurality of cylinder bores and at least one water hole. The gasket is basically formed by a first metal plate, and a second metal plate laminated together.
The first metal plate includes a plurality of first holes corresponding to the cylinder bores, an intermediate area between two first holes, at least one second hole corresponding to the at least one water hole and located in the intermediate area, and a continuous bead situated around the first and second holes. The bead has a linear common portion situated in the intermediate area, curved surrounding portions diverging from the linear common portion at an intersecting section near the at least one second hole to partly surround the first and at least one second holes, and a curved linking portion extending between the curved surrounding portions to partly surround the at least one second hole. The second hole is completely surrounded circularly by the curved surrounding portions and the curved linking portion.
The second metal plate has a main portion laminated on the first metal plate, third and fourth holes corresponding to the first and second holes, curved portions situated in the respective first holes, and flanges extending from the respective curved portions and located partly over the first metal plate to sandwich the first metal plate between the main portion and the flange. Each flange has a linear edge at the intermediate area to sandwich the linear common portion between two of the linear edges, and a curved edge surrounding the first hole.
In the metal gasket of the invention, since the periphery of the second hole, i.e. water hole, formed outside the bead intersecting portion between the adjacent first holes, i.e. combustion chamber holes, is surrounded and sealed by the curved surrounding portions and the curved linking portions, the water hole can be provided close to the center at the immediate portion outside of the bead intersecting portion.
The metal laminate gasket may further include a third metal plate laminated on the first metal plate to sandwich the first metal plate between the main portion and the flange of the second metal plate. The third metal plate includes a thick portion laminated on the bead and thin portions laminated on the flanges. Instead of forming the thick and thin portions, a fourth metal plate may be laminated on the third metal plate to be located at the continuous bead. Accordingly, the bead can provide a strong surface pressure when the gasket is compressed between the cylinder head and the cylinder block.